diff --git a/beets/library.py b/beets/library.py
index d9afac677..3ad875991 100644
--- a/beets/library.py
+++ b/beets/library.py
@@ -411,7 +411,7 @@ class FormattedItemMapping(dbcore.db.FormattedMapping):
 
     def __getitem__(self, key):
         """Get the value for a key. `artist` and `albumartist`
-		are fallback values for each other when unmapped.
+        are fallback values for each other when not set.
         """
         value = self._get(key)
 
@@ -419,11 +419,11 @@ class FormattedItemMapping(dbcore.db.FormattedMapping):
         # This is helpful in path formats when the album artist is unset
         # on as-is imports.
         if key == 'artist' and not value:
-	    new_value = self._get('albumartist')
+            new_value = self._get('albumartist')
             log.debug('No artist, using album artist {0}'.format(new_value))
             return new_value
         elif key == 'albumartist' and not value:
-	    new_value = self._get('artist')
+            new_value = self._get('artist')
             log.debug('No albumartist, using artist {0}'.format(new_value))
             return new_value
         else: